To decrease the probability of combustible or flammable materials within a fuel tank of an aircraft, current on-board inert gas generating systems (“OBIGGS”) typically comprise an air separation module (“ASM”) having a hollow-fiber membrane designed to produce and deliver a volume of nitrogen within the fuel tank's ullage. The increased percentage of nitrogen operates to reduce the concentration of combustible gases in the ullage and thereby, reduce the combustibility of the combined gasses. Typical OBIGGS utilize engine bleed air as the supply of pressurized inlet air for inert gas generation. However, over time, contaminants that are carried by that bleed air from the aircraft engines tend to build up and cause a drop in ASM performance that may eventually lead to system failure. Some of these contaminants may chemically react with the fiber material in such a way that the reaction results in permanent physical damage to the fiber material. Other contaminants (e.g., heavy hydrocarbons, oils, etc.) may condense within the hollow-fiber membrane so as to cause a reduction in available fiber surface area available to enable gas separation. When such a reduction in ASM performance occurs, performance may be recovered by removing the condensed contaminants from the surface of the hollow-fiber membrane.
To remove condensed contaminants, chemical cleansing methods, back-pulsing methods, and flashing methods have each been used in the past. However, these methods have been used on hollow-fiber membranes of ASMs designed for industrial and water filtration applications and not for OBIGGS operating aboard aircraft. As a result, such methods have been found to be difficult to implement on ASMs designed for the OBIGGS installed on aircraft due to contamination risks to other aircraft systems, uncertainty of the hollow-fiber membrane tolerances to cleaning agents and an inability to adequately perform cleaning methods on the installed ASM.
It is therefore an object of the present invention to address the disadvantages of these methods and further address the need for an efficient and reliable method to improve ASM performance on an OBIGGS unit.